BrazosDog02 said:
One of the three phases goes to a center tapped transformer and that transformer creates two phases out of it for residential?
Yes, although in many strictly residential areas it's pretty common to only have single-phase distribution on the primary side. My parents house in "old" N Dallas inside 635 has three phase service (hi leg delta) but my slightly newer house 10 miles north only has single phase, with no prayer of three phase being available because the distribution isn't there.
Edit: the "two phases" in typical residential setting is called "split single phase." You wind up with two hot legs (120 volts line to neutral) that are 180 degrees out of phase with each other. Hot to hot then gets you 240v. In a commercial/industrial setting with three phase service, the three hot legs are 120 degrees out phase with each other. Hot to hot gets you 208 volts.